TOLERANCE OF GROWING PIGS TO TRYPSIN AND CHYMOTRYPSIN INHIBITORS IN CHICKPEAS (CICER-ARIETINUM) AND PIGEONPEAS (CAJANUS-CAJAN)

The threshold level of growing pigs to trypsin and chymotrypsin inhibi tors was investigated by adding graded levels of meals rich in these i nhibitors to diets and recording responses. Diets were formulated to c ontain either 250, 500 or 750 g kg-1 of Opal chickpea, dehulled Tyson chickpea or dehulled pigeonpea meals and pig response compared to that of pigs given a wheat and soya-bean meal control. Trypsin inhibitor l evels (mg g-1) of the diets were, respectively, control, 0.2; chickpea meal 1, 1.2-3.2; chickpea meal 2, 1.7-4.7; pigeonpea meal, 1.4-3.6. C hymotrypsin inhibitor levels (mg g-1) of the diets were, respectively, control, 0.2; chickpea meal 1, 0.9-2-2; chickpea meal 2, 1.6-4.5; pig eonpea meal, 0.8-2.1. The diets were offered ad libitum over the 20-50 kg growth phase. Growth responses of the pigs fed the two chickpea me als were similar to those of the pigs fed the control soya-bean meal d iet (P > 0.05). In contrast, the addition of pigeonpea meal linearly d epressed growth rate (P < 0.001), feed intake (P < 0.05) and increased the feed conversion ratio (P < 0.05). inclusion levels of the chickpe a meals had no effect on organ weights, whereas the inclusion of pigeo npea meal significantly affected the weights of the liver and pancreas (P < 0.05), indicating the presence of other anti-nutritional factors . The results indicate that the growing pig can tolerate dietary level s of at least 4.7 and 4.5 mg g-1 of trypsin and chymotrypsin inhibitor s, respectively. These threshold levels are unlikely to be exceeded in conventional diets containing the majority of grain legumes. The resu lts also indicate that dehulled pigeonpea meal contains an anti-nutrit ional factor(s) for growing pigs.